---------------------------------------------------------------------- File: ftp://cher.media.mit.edu/pub/projects/6811/handy-board/hb-building-notes.txt Created by: Fred Martin (fredm@media.mit.edu) Last updated: Tue May 30 14:14:29 1995 ---------------------------------------------------------------------- This file contains some hints for assembling the Handy Board. It is assumed that you know how to build and solder. For an introduction to soldering and how to mount electronic components, see Chapter 1 of the 6.270 Robot Builder's Guide (ftp://cher.media.mit.edu/pub/projects/6270/docs-1992/chapter1.PS.Z). COMPONENT SIDE VERSUS SOLDER SIDE. The component side of the Handy Board is clearly marked "COMPONENT SIDE," near the location where the piezo speaker is installed. All components sit on the component side, with their leads poking through to the solder side. The board is then soldered from the solder side. Don't get it backward because the board won't work, unless you transport it to a parallel universe. THE SQUARE PAD CONVENTION. On the Handy Board, square pads have one of two meanings: * negative terminal. This applies to capacitors, LEDs, and diodes. * pin 1. This applies to integrated circuits and resistor packs. Following is information on the specific components that are polarized: * LED. Install so that cathode (negative terminal) goes into the square pad. If following the parts silkscreen, this is the shaded half of the LED circle. The cathode is indicated by either a flatted portion of the rim or the shorter of the two leads. * Diode. Install so that the cathode goes into the square pad. The cathode is marked with a band nearer to the cathod end. * Capacitors. If the capacitor is polarized (e.g., electrolytics and tantalum), either the + or - terminal will be marked. I.e., there may be a + marking indicating the + terminal, or a - marking indicating the - terminal. Figure out which is the - terminal and stick it in the square pad. If a capacitor is non-polarized (e.g., any value 0.1 uF or less), don't worry if the board has a square pad and a round pad. It doesn't matter how the capacitor is installed. * Integrated circuits. The square pad is pin 1. It's a nice idea to mount sockets so that its notch tells you where the notch on the chip goes. After soldering everything down it's harder to see where the square pads are. * Resistor packs. Most of these are polarized. The banded end is pin 1, which goes in the square hole. THE 6811. There is no square pad indicating pin 1 on the 6811. This is because a wire was in the way. Please refer to the parts placement diagram (hblayout.ps) to make sure you get the orientation of the 6811 socket correct. Remember, once the socket is soldered down, the 6811 only fits into it one way, so make sure the socket is soldered right. THE RAM AND THE LATCH. Repeating a hack on the 6.270 board, the 'hc373 address decoding latch (U3) mounts UNDERNEATH the memory chip (U2). Solder the 'hc373 directly to the PC board (making sure to get pin 1 in the right place). Then clip the internal supports away from the 28 pin DIP socket for the memory, allowing the socket to straddle U3. Solder down the socket and install the RAM. APPLYING POWER. It's generally a good idea to make sure the board is regulating the input voltage to five volts correctly before installing all of your ICs and turning the power on. Indeed, so as to possible save the regulator, first make sure there isn't a power-ground short before applying power at all. Measure resistance between +5v and ground and it shouldn't be zero. The trace running around the top of the board (top, right, and bottom edges) is +5v, and the trace around the bottom is ground. After checking continunity, apply power. Before you put all of the chips in their sockets, make sure there's a nice steady five volt power supply. Check voltage on one of the IC sockets; for example, on U5, pin 10 is ground and pin 20 is +5v. There's nothing you can do to protect U3 from faulty supply wiring (the address latch which is soldered straight down to the board). But that's no reason to blow every other chip on the board just out of haste. ----end----